The quality of a water supply can vary between sources and even from time to time within the same source. Certain substances can have negative effects when present in sufficient quantity in a user's water system. For example, hydrogen sulfide (H2S) is a notorious chemical, being widely known and well-recognized by smell, if not always by name. The characteristic “rotten egg” odor of H2S is almost universally reviled. Thus, the presence of a significant quantity of H2S, i.e., enough to be readily detected by ordinary olfactory perception, within a building, and in particular a residence, is undesired.
However, when conditions are favorable, H2S may be spontaneously generated in a water heater appliance. For example, H2S may be generated from reduction of sulfate (SO4) ions. As such, a sufficient amount of SO4, which can be naturally-occurring in a water supply, along with sulfate reducing bacteria and/or necessary thermochemical conditions, may eventually create a bad smelling/tasting condition from the water heater in the user's home. Therefore, because sulfate is a precursor to odiferous H2S, there is a need to identify when naturally-occurring sulfates are present in the water heater tank such that the user can be alerted and then can take proactive steps to prevent H2S generation.
Electrochemical sensors which detect sulfide are generally known. However, such electrochemical sulfide sensors are limited in their operating range in that they require very basic (e.g., pH>11) conditions and are therefore generally not usable in residential water heaters. Also, earlier detection of a potential problem, e.g., by detecting precursors rather than the malodorous compound itself, is more desirable.
Accordingly, a water heater appliance with features for detecting precursors prior to the formation of odor-causing compounds would be useful.